Strong, lightweight article, containing a fine-grained metallic layer

ABSTRACT

Articles for automotive, manufacturing and industrial applications including shafts or tubes used, for example, as golf club shafts, ski and hiking poles, fishing rods or bicycle frames, skate blades and snowboards are at least partially electroplated with fine-grained layers of selected metallic materials. Parts with complex geometry can be coated as well. Alternatively, articles such as conical or cylindrical golf club shafts, hiking pole shafts or fishing pole sections, plates or foils and the like can also be electroformed of fine-grained metallic materials on a suitable mandrel or temporary substrate to produce strong, ductile, lightweight components exhibiting a high coefficient of restitution and a high stiffness for use in numerous applications including sporting goods.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. application Ser. No. 12/000,582,filedDec. 14, 2007 which is a continuation of U.S. application Ser. No.11/013,456,filed Dec. 17, 2004.

FIELD OF THE INVENTION

This invention relates to the electrodeposition of thick (>30 μm), finegrained coatings (average grain size 4 nm to 10,000 nm) of a pure metal,a metal alloy or metal matrix composite with high resilience (>0.25 MPa)at high deposition rates (>25 μm/hr) to articles for automotive (e.g.running boards, spoiler, muffler tips), and manufacturing applicationsincluding tubes or shafts as used e.g. in sporting goods such as ski andhiking poles, fishing rods, golf club shafts, hockey sticks, bicycleframes, skate blades, snow boards; plates such as golf club head faceplates; as well as complex shapes such as sports racquets (tennis,racquetball, squash and the like), golf club heads and the like. Partsare at least partially electroplated with said fine-grained layers ofselected metallic materials.

The invention also relates to electroforming such fine-grained metallicmaterials onto suitable mandrels such as a cylindrical, conical ortapered shaft, or other temporary substrate as well as plates or foilsand the like for the production of strong, ductile, lightweightcomponents requiring a high modulus of resilience, a high coefficient ofrestitution and a high torsional stiffness for use e.g. in sportinggoods, as well as the automotive, and industrial applications.

BACKGROUND OF THE INVENTION

In a large number of sporting goods and industrial applications, thearticle of interest must be strong, wear resistant, lightweight anddisplay high resilience, high flexural stiffness at room temperature aswell as elevated temperature (e.g. up 200° C.) while having beenmanufactured by a convenient and cost-effective method.

Harmala in U.S. Pat. No. 5,320,386 (1994) describes a lightweight, highstrength, composite titanium ski pole. The composite shaft includes ahollow first shaft of a titanium alloy and a hollow second shaft ofstiffening material. The first and second shafts are assembled to havethe exterior surface of one of the shafts in surface-to-surface contactwith an interior surface of the other one. By employing the stiffeningtube in conjunction with the titanium alloy tube, the titanium alloytube is still permitted to bend, but is substantially prohibited frombending in an amount which would approach its yield point and result inpermanent deformation.

Sandman in U.S. Pat. No. 5,538,769 (1969) describes a graphite compositeshaft with a reinforced tip, suitable for use in fishing rods or golfclubs. The shaft includes a base shaft made at least partially ofgraphite composite material provided in one or more layers or plies.These shafts have relatively slender tips that are normally prone toimpact damage.

Fishing rod tip failure/breakage is a major cause of warranty returns offishing rods to the manufacturer. In addition, as golf clubs are swungin close proximity to the ground, it is not unusual for the club head tostrike the ground with considerable force, applying a large force ortorque to the narrowest portion of the shaft, i.e. to the tip of theshaft that is joined to the club head. This impact can cause failure ofthe composite shaft at this point, causing the tip of the shaft to breakat or closely adjacent the club head. The reinforcement layer describedin this patent, which extends only part of the way up the length of thebase shaft, is intended to render the shaft more resistant to impactsoccurring at the tip and increase the durability of the shaft withoutdecreasing the performance of the fishing rod or golf club thatincorporates the shaft.

Perryman in U.S. Pat. No. 6,354,960 (2002) describes a golf club shaftwith controllable feel and balance using a combination offiber-reinforced plastics and metal-coated fiber-reinforced plastics toobtain an individually optimized golf club. A filament-wound outer layerhaving at least one ply including metal-coated fibers covers asheet-rolled or filament-wound core. The fibers can be metal-coated withmetals such as nickel, titanium, platinum, zinc, copper, brass,tungsten, cobalt, gold or silver. The use of metal-coated fibers permitsthe use of combinations of fiber reinforced plastic and metal-coatedfibers in producing golf shafts with optimum performance properties.Specific placement of the metal-coated fibers makes it possible to addweight to predetermined points in the shaft in order to shift the flexand balance points without varying the torsional properties of the shaftand to provide the optimum flex for a given golf club design.

Yanagioka in U.S. Pat. No. 4,188,032 (1980) discloses a nickel-platedgolf club shaft made of fiber-reinforced material having onsubstantially its entire outer surface a metallic plating selected fromthe group consisting of nickel and nickel based alloys for the purposeof providing a wear-resistant coating. The electroless nickel coating ofchoice is 20 μm thick and the deposition time is 20 hrs, resulting in adeposition rate of 1 μm/hr.

Kim in U.S. Pat. No. 4,951,953 (1990) describes a golf club electrolesscoated with a high Young's Modulus material (≧50 million psi) or with acomposite material having a high Young's Modulus material as asubstantial ingredient in the matrix. Diamond is particularly preferredas a coating or coating component due to its high strength andrelatively low density. The coating may be applied, for example, usingan electroless “composite diamond coating” technique, to either the heador shaft of the club, the club head only or the shaft only to provideimproved directional accuracy and impact performance characteristics.The coating is typically applied using an electroless “composite diamondcoating” technique, to either only the striking face of the club heador, preferably, to a substantial portion of the shaft below the grip andover the club head continuously over the junction between the shaft andclub head. The coating thickness ranges from about 1 to 2 mils (25 μm to50 μm), although 1-10 mil (25 μm to 250 μm) thick coatings are noted andthe particle size of the coating material is from about 0.1 μm to 50 μmwith a preferred range of 1 μm to 10 μm.

Chappel in U.S. Pat. No. 6,346,052 (2002) discloses golf club irons withmultilayer construction. The golf club head comprises a soft nickelalloy core and a hard chrome coating. The process used to produce thegolf club heads involves an investment casting process in which the softnickel alloy core is cast and the hard chrome coating is electroplatedonto the core. This multilayer design produces a golf club iron that isdurable and consistent from iron to iron with feel characteristics whichare generally equal to or better than traditional clubs formed fromforged mild carbon steel. Unlike the decorative chrome used on prior artgolf clubs (hardness of about 35 to 45 Rockwell C, typical thicknessbetween 0.05 to 0.2 mil) the chrome outer layer used in the invention isbetween 0.8 mils to about 1 mil (20 μm to 25 μm) thick, which is atleast four times thicker than conventional applications of decorativechrome in prior art clubs. The hard chrome plating employed is assertedto provide durability without compromising the superior feelcharacteristics of the relatively soft nickel alloy core when a golfball is struck.

Takeda in U.S. Pat. No. 5,935,018 (1999) describes a golf club andmethod of manufacturing intended to prevent copper or copper alloymaterial used in the head from corroding. The invention also aims atpreventing galvanic corrosion when combining such materials with othermaterials, such as aluminum alloys, by applying a nickel-plated coatinglayer to the head, followed by chrome plating.

Umlauft in U.S. Pat. No. 6,106,417 (2000) describes a lightweight tennisracket with a high stiffness. The racket is formed from a compositematerial including carbon fibers, titanium fibers, and epoxy resin andis at least 27 inches long, weighs less than 9.2 ounces when strung, andhas a frequency of vibration of the first mode of bending underfree-free constraint of at least 175 Hz. To achieve the lightweight,high strength properties, the carbon-reinforced composite isstrengthened particularly in the racket throat area with metallictitanium fibers.

Numerous publications describe sport racquets reinforced and stiffenedby structural straps or plates at the outer or inner surfaces, or withinthe wall of the handle and frame, including Stauffer (U.S. Pat. No.3,949,988 (1976), Matsuoka in JP2000061005 (1998) and JP09285569 (1996).

Reed in U.S. Pat. No. 5,655,981 (1997) describes a shaft for a hockeystick comprising a non-metallic elongated material member; a first layercomprised of a resilient yet tough material bonded to the member; asecond layer comprised of metal applied to the first layer by a metaldeposition process; and a third layer comprised of a clear, resilient,tough material encasing said second layer of metal. The thin metalliclayer is applied to the substrate by a vapor vacuum deposition process.The base layer, metallic layer and top layer have an overall thicknessof less than approximately 3 mil. The purpose of the thin metallic layerapplied to a non-metallic shaft, having a maximum thickness of 0.01 mil(0.25 μm), is entirely to enhance the appearance and the metals ofchoice include aluminum, copper, gold and silver.

Burns in U.S. Pat. No. 4,124,208 (1978) discloses a durable, lightweighthockey stick having opposed metal outer skins made of a single pieceincluding the shaft and integral handle and blade portions with a metalhoneycomb sandwiched there between. The metal hockey stick provides longlife at an overall weight similar to that of wood and is relativelyinexpensive.

Erb in U.S. Pat. Nos. 5,352,266 (1994), and 5,433,797 (1995) describes aprocess for producing nanocrystalline materials, particularlynanocrystalline nickel. The nanocrystalline material is electrodepositedonto the cathode in an aqueous acidic electrolytic cell by applicationof a pulsed DC current. The cell also optionally contains stressrelievers. Products of the invention include wear resistant coatings,and magnetic materials.

Palumbo WO2004/001100 A1 (2002) discloses a process for forming coatingsor freestanding deposits of nanocrystalline metals, metal alloys ormetal matrix composites. The process employs drum plating or selectiveplating processes involving pulse electrodeposition and optionally anon-stationary anode or cathode, Novel nanocrystalline metal matrixcomposites are disclosed as well. Also described is a process forforming micro-components with grain sizes below 1,000 nm.

Although a number of electrolytic and electroless plating processes areknown to provide metallic coatings to the surfaces of various articlessuch as golf club heads, shafts and the like, heretofore theelectrodeposited metallic coatings used are thin (limited typically toless than 25 μm) and applied primarily for scratch and corrosionresistance.

Electroless coating deposition rates are low, typically 0.25 mil/hr(6.25 μm/hr) to 0.5 mil/hr (12.5 μm/hr) whereas galvanic coatingdeposition rates typically exceed 1 mil/hr (25 μm/hr). The typicalcoating thickness values for electroless plating processes are less than1 mil (25 μm). In the case of electrolytic coatings it is well knownthat after the coating has been built up to a thickness of about 5-10μm, it tends to become highly textured and grows in a fashion wherebyanisotropic and elongated columnar grains prevail with typical grainwidths of a few microns and grain lengths of tens of microns. Prior artthin coatings applied by electroless or conventional electroplatingprocesses exhibit amorphous or conventional grain size values (≧5 μm)and do not significantly improve the overall mechanical properties ofthe coated article.

Substantial grain size reduction has been found to strongly enhanceselected physical, chemical and mechanical properties of a coating. Forexample, in the case of nickel, the ultimate tensile strength increasesfrom 400 MPa (for conventional grain-sizes greater than 5 μm) to 1,000MPa (grain size of 100 nm) and ultimately to over 2,000 MPa (grain size10 nm). Similarly, the hardness for nickel increases from 140 VHN (forconventional grain-sizes greater than 5 μm) to 300 VHN (grain size of100 nm) and ultimately to 600 VHN (grain size 10 nm) We thereforeexpected that the application of coatings of this kind could improve thedurability and performance characteristics of structural components ofsporting equipment and other equipment or parts requiring strong,ductile and lightweight components.

OBJECTS AND SUMMARY OF THE INVENTION

It is an objective of the invention to provide articles for use asautomotive parts, and industrial components, including sporting goodsarticles, having a structural metallic layer by applying a thick,coarse-grained or preferably fine-grained metal, metal alloy or metalmatrix composite layer of high resilience by electrodeposition to ametallic or non-metallic substrate to enhance the overallstrength-to-weight ratio, improve the damping characteristics and/or toprovide external or internal surfaces of high resilience, high yieldstrength, scratch and wear resistance and hardness, and appealingappearance.

It is an objective of the invention to apply an isotropic orquasi-isotropic metallic coating or layer by electrodeposition,minimizing formation of columnar, elongated grains and any undesirablecrystallographic texture.

It is an objective of the invention to apply the metallic coating to atleast part of the surface of an article made substantially of a polymermaterial or graphite fiber composite, optionally after rendering thesurface conductive e.g. by coating the surface with a thin layer ofelectroless nickel, copper or the like or by applying chemically reducedsilver spray.

It is an objective of this invention to provide a process capable ofnet-shape electroforming fine-grained metallic articles such as golfclub face plates as well as tubes, shafts and complex forms for use in avariety of applications.

It is an objective of this invention to provide shafts or tubes e.g. foruse as golf clubs, hockey, ski or hiking pole shafts or fishing polesand tubes for use in bicycle frames, automotive and industrialcomponents and the like that are lightweight, resistant to abrasion,resistant to permanent deformation and do not splinter when cracked orbroken.

It is an objective of this invention to at least partially coat theinner or outer surface of parts including complex shapes such asracquets e.g. for tennis, squash, badminton, etc, baseball bats, skis,golf club face plates and/or heads or other sporting equipment,automotive and industrial components with a material that is strong andlightweight.

It is an objective of the invention to provide sporting goods that arestrong, wear resistant, lightweight and display high resilience, whilebeing manufactured by a convenient and cost-effective method.

It is an objective of the invention to provide articles with strong,hard, fine-grained layers which can be further hardened by applying asuitable heat treatment after electroplating/electroforming.

It is an objective of the invention to provide a golf club capable ofachieving increased flight distance performance, provide increasedcontrol over the club shaft and head and/or provide improved golf ballflying distance and accuracy characteristics, as well as improvedvibration damping characteristics at low overall weight.

It is an objective of the invention to apply a fine-grained metal, metalalloy or metal matrix composite layer coating using electrodeposition toat least part of the inner or outer surface of an article including agolf club head comprising a substrate selected from:

-   -   (i) an undersized cast or forged article (e.g. golf club head        made of e.g. plain carbon steel); or    -   (ii) a plastic preform (e.g. ABS, polycarbonate, e.g. injection        molded); or    -   (iii) metal article inserts (e.g. removable golf club driver        faceplates);        in order to achieve e.g. in the case of a golf club head    -   (a) a high resilience face area providing increased driving        distance for the golf ball;    -   (b) damping characteristics providing superior “sound” and        “feel” when e.g. striking a golf ball;    -   (c) high strength-to-weight ratio allowing strategic perimeter        weighting of the club head; and    -   (d) an external surface of high hardness for improved scratch        and wear resistance.

With a view to achieving these objectives and improving the propertiesof commercial articles, in particular sporting equipment, automotiveparts, and industrial components, the invention according to oneembodiment provides an article with an electrodeposited metal or metalalloy coating having a thickness of between 30 μm and 5 mm and up to asmuch as 5 cm and a quasi-isotropic microstructure, the coatingexhibiting the resilience of at least 0.25 MPa and up to 25 MPa and anan elastic strain limit of at least 0.75% and up to 2.00%. Articles orequipment to which the invention has particular applicability includegolf club shafts, including graphite golf club shafts.

According to a further embodiment of the invention, electroformedmetallic components are provided for various applications includingsporting equipment in which the microstructure of the component isquasi-isotropic and exhibits an average grain size between 0.004 μm and10 μm and a yield strength of between 200 MPa and 2,750 MPa, for examplean electroformed golf club shaft.

Graphite/metal composite articles such as golf shafts incorporating ametallic coating representing at least 5%, preferably more than 10% andeven more preferably more than 20% and up to 75%, 85% or 950% of thetotal weight on a polymer substrate optionally containinggraphite/carbon fibers are disclosed. The torsional stiffness per unitweight of the article containing the metallic coating is improved by atleast approximately 5% when compared to the torsional stiffness of thesame article not containing the metallic coating.

GENERAL DESCRIPTION OF THE INVENTION

The process for producing articles and components of sporting equipmentaccording to the invention comprises the steps of, positioning themetallic or metallized work piece or the reusable mandrel/temporarysubstrate to be plated in a plating tank containing a suitableelectrolyte, providing electrical connections to the mandrel/temporarysubstrate to be plated and to one or several anodes, forming andelectrodepositing a metallic material with an average grain size of lessthan 1,000 nm on at least part of the surface of the work piece using asuitable D.C. or pulse electrodeposition process described in thecopending application, WO 2004/001100 A1 (2002). Patent Publication WO2004/001100 A1 is incorporated herein by reference for its teaching ofelectrodeposition techniques which may be used in the preparation ofsporting goods articles according to the present invention.

Deposition rates required are at least 25 μm/h, preferably 50 μm/h andmore preferably greater than 75 μm/h, by passing single or multiple D.C.cathodic-current pulses between said anode and said work piece area tobe plated, i.e. the cathode, at a cathodic-current pulse frequency in arange of approximately 0 to 1,000 Hz, at pulsed intervals during whichsaid current passes for a t_(on)-time period of at least 0.1 msec,typically in the range of about 0.1 to 50 msec and does not pass for at_(off)-time period in the range of about 0 to 500 msec, and passingsingle or multiple D.C. anodic-current pulses between said cathode andsaid anode at intervals during which said current passes for at_(anodic)-time period in the range of 0 to 50 msec, a cathodic dutycycle being in a range of 5 to 100%. Suitable plating processes includetank, rack, barrel, brush and drum plating.

The novel process can be applied to establish high-strength coatings ofpure metals or alloys of metals selected from the group of Ag, Au, Cu,Co, Cr, Ni, Sn, Fe, Pt and Zn and alloying elements selected from Mo, W,B, C, P, S and Si and metal matrix composites of pure metals or alloyswith particulate additives such as powders, fibers, nanotubes, flakes,metal powders, metal alloy powders and metal oxide powders of Al, Co,Cu, In, Mg, Ni, Si, Sn, V, and Zn; nitrides of Al, B and Si; C(graphite, diamond, nanotubes, Buckminster Fullerenes); carbides of B,Cr, Bi, Si, W; and self lubricating materials such as MoS₂ or organicmaterials e.g. PTFE. The process can be employed to create highstrength, equiaxed coatings on metallic components, or non-conductivecomponents that have been metallized to render them suitable forelectroplating. In an alternative embodiment, the same process can beused to electroform a stand-alone article on a mandrel or other suitablesubstrate and, after reaching the desired plating thickness, to removethe free-standing electroformed article from the temporary substrate.

The following listing describes suitable operating parameter ranges forpracticing the invention:

Metallic Layer Thickness Minimum: 30 μm Metallic Layer ThicknessMaximum: 5 mm, up to 5 cm Average Grain Size Range: 0.004 μm to 10 μmMinimum Ratio Coating Thickness 25; 100; 1,000 to Grain Size: MaximumRatio Coating Thickness 10,000; 100,000; to Grain Size: 1,250,000;12,500,000 Deposition Rate Range: 10-500 μm/hr Duty Cycle Range: 5 to100% Yield Strength Range: 200 MPa to 2750 MPa Minimum Modulus ofResilience 0.25 MPa, 1 MPa, of the Electrodeposited Layer: 2 MPa, 5 MPa,7 MPa Maximum Modulus of Resilience 12 MPa, 25 MPa of theElectrodeposited Layer: Elastic Limit Range: 0.75%-2.00% ParticulateContent Range: 2.5% to 75% by Volume Deposition Temperature Range: 10 to100° C.

In the process of the present invention the electrodeposited metalliccoatings optionally contain at least 2.5% by volume particulate,preferably at least 5% and up to 75% by volume particulate. Theparticulate can be selected from the group of metal powders, metal alloypowders and metal oxide powders of Al, Co, Cu, In, Mg, Ni, Si, Sn, V,and Zn; nitrides of Al, B and Si; C (graphite or diamond); carbides ofB, Cr, Si, W; MoS₂; and organic materials such as PTFE and otherpolymeric materials. The particulate average particle size is typicallybelow 10,000 nm (10 μm), 5,000 nm (5 μm), 1,000 nm (1 μm), and morepreferably below 500 nm.

The present invention provides for electrodeposited fine-grained layers,having a thickness of at least 0.030 mm, more preferably more than 0.05mm and even more preferably more that 0.1 mm on the surface ofappropriate articles, including golf club heads, inserts for golf clubheads, face plates for golf clubs; shafts for golf clubs, hockey sticks,hiking and skiing poles, etc. and coatings to complex shapes e.g.baseball bats, skate blades, snow boards and tennis rackets.

The electrodeposited metallic fine-grained layers of this invention havean average grain size under 10 μm (10,000 nm), preferably in the rangeof 4 to 750 nm, more preferably between 10 and 500 nm and even morepreferably between 15 nm and 300 nm.

The electrodeposited fine-grained layers of this invention have amodulus of resilience of at least 0.25 MPa, preferably at least 1 MPa,more preferably at least 2 MPa, more preferably at least 5 MPa and evenmore preferably at least 7 MPa and up to 25 MPa.

The electrodeposited fine-grained layers of this invention have anelastic limit of at least about 0.75%, and preferably greater than about1.0%; and preferably greater than 1.5% and up to 2.00%.

In a preferred embodiment, the present invention provides an equiaxedmicrostructure throughout the plated component, which is relativelyindependent of component thickness, shape and part orientation in theplating cell.

To ensure part reliability, it is preferable to maintain the averagethickness to average grain size ratio of the coated layer at a minimumvalue of 25, preferably greater than 500, and more preferably greaterthan 1,000; and up to 1,250,000 and as much as 12,500,000.

In a preferred embodiment of the process of this invention, dispersionstrengthening of metallic coatings is performed by a subsequentheat-treatment.

According to this invention, patches or sections can be formed onselected areas (e.g. golf club face plates or sections of golf clubshafts, bats, racquets, frames for bicycles and the like), without theneed to coat the entire article.

According to this invention patches or sleeves which are not necessarilyuniform in thickness can be electrodeposited in order to e.g. enable athicker coating on selected sections or sections particularly prone toheavy use such as golf club face plates, the tip end of fishing polesand shafts for golf clubs, skiing or hiking poles etc.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to better illustrate the invention by way of examples,descriptions are provided for suitable embodiments of themethod/process/apparatus according to the invention in which:

FIG. 1 is a frontal view of a golf club head utilizing a clubface platecoated with the ultra-fine grained metallic material as theball-contacting surface.

FIG. 2 is a cross-sectional view of the electrodeposited layer appliede.g. to golf club ball-striking surfaces, shafts of poles for golfclubs, ski poles and hiking poles, in accordance with one embodiment ofthis invention.

FIG. 3 is a perspective view of a golf club including a golf club shafthaving a fine-grained outer layer in accordance with the teachings ofthe present invention.

FIG. 4 is a partial perspective cross-sectional view of the shaft ofFIG. 3 including a fine-grained layer deposited along a selected lengthof the shaft's outer surface.

FIG. 5 shows the torsional stiffness as a function of the metal contentof graphite/metal composite golf shafts containing a coarse grained orfine-grained layer deposited along a selected length of the shafts'outer surface.

FIG. 6 schematically depicts the microstructural featuresdifferentiating columnar (6 a) from quasi-isotropic/equiaxed (6 b) grainstructures. “Columnar” in this context refers to a grain shape orstructure, which typically starts with one size upon initiation of theplating on the substrate. With increased layer thickness and platingtime the grains become progressively larger and align with a certaincrystallographic orientation relative to the substrate. The localaverage grain size distribution of columnar grain structures changes andprogressively increases from the substrate to the outer surface.“Quasi-isotropic/equiaxed” in this context refers to grains that exhibitsome crystallographic texture but are reasonably uniform in shape andsize, exhibiting a grain size distribution which is similar throughoutthe deposit.

The present invention is intended for depositing preferably fine-grainedquasi-isotropic layers onto articles in the form of external or internalcoatings or electroforming articles comprising a metal or alloy selectedfrom Cu, Co, Cr, Ni, Fe, Sn, Mo and Zn optionally with particulatedispersed in the fine-grained layer.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

This invention relies on producing fine-grained, quasi-isotropic,equiaxed coatings by DC or pulse electrodeposition.

The person skilled in the art of plating, in conjunction e.g. with U.S.Pat. Nos. 5,352,266 (1994), 5,433,797 (1995) and in PCT/EP02/07023(2002) cited already, will know how to electrodeposit selected metals oralloys by selecting suitable plating bath formulations and platingconditions. These patents are incorporated herein by reference for theirdisclosure of electrodeposition methods. Optionally, solid particles canbe suspended in the electrolyte and are included in the deposit asdescribed in PCT/EP02/07023, filed on Jun. 25, 2002.

Minimizing the thickness and weight of articles for numerousapplications can be achieved by increasing the strength through grainsize reduction. Depending on the ductility required, the grain size ofe.g. Ni-based coatings in the range of 4 nm to 10,000 nm, preferably 10nm to 500 nm provides a coating with suitable mechanical properties.Incorporating a sufficient volume fraction of particulate can be used tofurther enhance the material properties.

Depending on the requirements of the particular application, thematerial properties can also be altered e.g. by incorporating drylubricants (such as MOS₂ and PTFE), abrasion or wear resistantparticles. Generally, the particulates can be selected from the group ofmetal powders, metal alloy powders and metal oxide powders of Al, Co,Cu, In, Mg, Ni, Si, Sn and Zn; nitrides of Al, B and Si; C (graphite,diamond, nanotubes, and/or Buckminster Fullerenes); carbides of B, Si,W; self lubricating materials such as MoS₂, organic materials such asPTFE and polymeric materials.

As noted above, particularly suited applications of the fine-grainedlayers disclosed herein include golf shafts, ski poles, fishing rods,hockey sticks, tennis racquets, bicycle frames and other articles andstructures comprised of conventional metal, polymer or graphitecomposites that are coated on at least part of the interior and/orexterior surfaces, or, alternatively are net-shape electroformed withthe use of a temporary substrate. Conventional metals e.g. aluminum,titanium, steel and their alloys are relatively soft, permanently deformand break easily as a result of the bending and torsional loadsencountered during use. Furthermore, these conventional materialsgenerally exhibit a low resistance to abrasion and cut or scratch easilyand can benefit from the fine-grained metallic layer described in thisinvention. Shafts made from composites of synthetic resins and filamentsare more resilient under bending forces than aluminum, but lacksufficient strength. This deficiency, however, can be overcome byapplying a fine-grained metallic layer according to the presentinvention.

The rebound distance of an object, e.g. a golf ball, tennis ball,baseball or the like when it impacts a certain material is a function ofthe modulus of resilience, Ur, of the material, which is expressed as:

$U_{r} = {{\frac{1}{2}\sigma_{y}ɛ_{y}} = \frac{\sigma_{y}^{2}}{2E}}$

(Metals Handbook, Ninth Edition, Volume 8, Mechanical Testing, AmericanSociety for Metals, Materials Park, Ohio, 44073)

Where ε_(y) is the maximum true strain at the yield point, σ_(y)represents the yield strength and E the modulus of elasticity. Asfine-grained materials described in this invention possess yieldstrength values, σ_(y), which are three to five and up to ten timesgreater that those of conventional coarse-grained metals, the resilience(rebound distance capacity) can therefore be increased nine to twentyfive-fold and up to hundred fold. The modulus of elasticity E, however,is typically not affected by reducing the grain size of a given metallicmaterial, provided the material is fully dense. The modulus ofelasticity, however, can be altered e.g. by using metal matrixcomposites.

Material properties required for a number of applications also include ahigh elastic strain-to-failure limit. Low damping characteristics (lowabsorption and high re-release of energy) ensures that even after highload and stress deformation the material springs back to its originalshape as required on strike faces for e.g. golf head face plates andbaseball bats. Conventional metals have elastic strain limits of 0.65%or less. The current invention is directed to metallic materials havingelastic limits of at least about 0.75%, preferably greater than about1.0%; and preferably greater than 1.5% and up to 2.00%.

FIG. 1 illustrates a frontal view of a golf club 70 having a shaft 72and a head 74 attached at one end of the shaft 72. A faceplate 76 of thehead 74 includes a plurality of grooves 78. The faceplate 76 contains alayer of the fine-grained material of high strength and resilience and alow coefficient of friction. In one embodiment, the entire head 74 iscoated with the fine-grained material. In an alternate embodiment thefaceplate 76 contains or is coated with the fine-grained material. Thefine-grained material optionally contains solid particles dispersedthroughout the layer including ceramic particulate (e.g. TiO₂, WC, B₄C)to improve hardness, wear resistance and yield strength and/or alubricating material (erg. MoS₂, PTFE, and other fluoropolymers).

Carbon fiber composites possess much higher specific rigidity and lowerdensity than steel; however, the light-weight, carbon-fiber golf shaftsoften exhibit undesirable twisting of the club head relative to theshaft on down-swing and particularly at ball contact, resulting in pooraccuracy and flying distance. This limitation can be overcome by coatingat least 10% of the composite shaft's external and/or internal surfacewith the fine-grained metallic layer described.

FIG. 2 illustrates a cross-sectional view of the fine-grainedelectrodeposited layer containing solid particles, applied to an articlee.g. to golf club ball-striking surfaces, shafts of poles for golfclubs, ski poles and hiking poles 82 in accordance with the presentinvention. The layer with the outer surface 84 includes a metallicmatrix material 86, as well as the surface 88 of a particulate(lubricant, high strength, low wear rate, and/or appealing appearance)material 90. The particulate material 90 has been distributed throughoutthe matrix material 86.

A golf club incorporating any one of a number of different shafts inaccordance with the teachings of the present invention is shown in FIG.3 and is designated generally by the reference numeral 10. As shown, thegolf club 10 includes a generally conical shaft 12 formed along thelongitudinal axis A_(x) with a grip 14 attached at its upper end 16 anda club head 18 attached at its lower end 20. The shaft 12 is typicallytapered downward from the upper end 16 to the lower end 20, with thelower end 20 of the shaft 12 being received within a hosel 22 of thegolf club head 18 as is conventional in the art. The shaft 12 includes afine-grained layer that covers at least part of the selected lengthdimension along the shaft 12. As will be described in greater detailbelow, this fine-grained metallic layer can be applied as a coating toat least part of the metal or composite shaft or, in an alternativeembodiment, can be electroformed to yield the shaft 12.

As shown particularly in FIG. 4, the shaft 12 is fabricated by applyinga fine-grained coating 28 to the metallic (e.g. steel) or polymercomposite (carbon fiber/epoxy) shaft 26 on its outer surface. The grainstructure of the deposit is quasi-isotropic and equiaxed as displayed inFIG. 6 b.

It should be noted that the shaft or part 12 providing the substrate forthe fine-grained quasi-isotropic metal or metal composite layer coatingof the present invention can be formed from a variety of differentmaterials and multiple layers thereof. By way of example, parts can bemade from both metallic and non-metallic materials and combinations ofboth metallic and non-metallic materials. Metals considered suitable forthe production of components, e.g. golf club shafts include aluminum,titanium, steel, stainless steel, copper, brass, bronze, zinc,magnesium, tin and nickel, or their alloys.

Various non-metallic materials, which are now commonly used in themanufacture of golf club shafts or other sporting goods parts as well asvarious automotive, or industrial articles, include polymeric resinmatrix composites employing materials including carbon fibers, ceramicmatrix, aramid fibers, polyethylene fibers, boron, fiberglass, andvarious thermoplastics including, but not limited to, polypropylene,polyethylene, polystyrene, vinyls, acrylics, nylon and polycarbonates,among others.

The present invention is particularly suitable for graphite-containingarticles including golf club shafts or other sporting goods. As allarticles can be rendered suitable for electroplating by applying a thinlayer of a conductive material e.g. by electroless deposition, physicalor chemical vapor deposition, or applying electrically conductive paintsby chemical vapor deposition, or applying electrically conductive paintsby various suitable means, it should be clear to those skilled in theart that the subject invention encompasses the use of virtually anysubstrate material.

According to a further preferred embodiment of the present invention, itis also possible to produce fine-grained coatings by electroplatingwithout the need to enclose the area of the article to be coated andform a plating bath around it. Brush or tampon plating is a suitablealternative, particularly when only a small portion of the work-piece isto be plated. The brush plating apparatus typically employs adimensionally stable or soluble anode wrapped in an absorbent separatorfelt to form the anode brush. The brush is rubbed against the surface tobe plated in a manual or mechanized mode and electrolyte solutioncontaining ions of the metal or metal alloys to be plated is injectedinto the separator felt.

EXAMPLE 1 Electroformed Article—shaft, Ni—Mo

A freestanding golf club shaft comprised entirely of fine-grained,nanocrystalline Ni—Mo (Mo content≦2%) was electroformed on a Cr-platedsteel mandrel (OD₁=0.600″, tapering down to OD₂=0.335″ over a length of42″) in a modified Watts nickel bath and using a Dynatronix(www.dynatronix.com, Dynanet PDPR 40-100-400) pulse power supply. Theelectrolyte used comprised 300 g/l nickel sulfate, 45 g/l nickelchloride, 45 g/l boric acid, 4 g/l sodium molybdate, 2 g/l saccharin and5 ml/l NPA-91 (www.atotechUSA.com supplied wetting agent). Standardlevelers, brighteners, stress relievers and chelating agents wereemployed and nickel “R”-rounds (www.inco.com) were used as anodematerial. The electroplating conditions and metallic layer propertiesused are summarized in Table 1.1.

TABLE 1.1 Electroplating Conditions Deposition Temperature [° C.] 62Duty Cycle [%] 30 Deposition Rate [μm/hr] 75 Average Coating Thickness:[μm] 325 Average Grain Size: [μm] 0.035 Ratio Coating Thickness/GrainSize 9,286 Yield Strength [MPa] 1035 Hardness [VHN] 540

The electroformed nano Ni/Mo shaft was removed from the temporarysubstrate. Due to the partial shielding of the anodes, the shaft wallthickness increased from 300 micron at the handle (OD₁) to 380 micron atthe tip (OD₂). This particular shaft, a graphite shaft and a steel shaftof similar weight were equipped with Pro Steel #4 Iron heads andsubmitted to Golf Laboratory Inc. (www.golflabs.com) for computercontrolled robotic performance testing. Six individual measurements weretaken for each test condition. Table 1.2. illustrates that the averageball dispersion and distance (higher lift angle, higher ball velocityand reduced ball spin rate) characteristics of the electroformed shaftare improved when compared to both graphite and steel shafts.

Particularly noteworthy is the substantial improvement in balldispersion for “off center hits”.

One sample was cross sectioned. The microstructure of the plated layerwas confirmed to be quasi-isotropic as illustrated in FIG. 6 b.

Other parts composed of nickel, cobalt or iron based alloys withdifferent geometries including tubes, plates and the like were alsosuccessfully formed using the same process.

TABLE 1.2 Golf Club Robotic Test Results GRAPHITE, STEEL- GRAPHITE,STEEL- GRAPHITE, STEEL- UST STD, UST STD, UST STD, ProForce ‘S’ ThisProForce ‘S’ This ProForce ‘S’ This Shaft 95 ‘S’ Flex Flex Invention 95‘S’ Flex Flex Invention 95 ‘S’ Flex Flex Invention Description CenterHits ½″ Toe Hits ½″ Heel Hits Carry 161.7 164.6 164.9 158.4 158.8 161.7163.2 165.7 166.0 Distance [m] Carry 1.16 0.94 1.25 5.54 3.29 1.71 4.636.00 1.71 Dispersion [m] Total 168.2 169.8 176.8 164.3 165.5 168.1 170.4172.4 173.6 Distance [m] Total 1.74 1.37 1.62 5.94 3.51 2.07 4.51 6.802.16 Dispersion [m] Ball 139.4 139.7 140.8 134.3 134.7 135.7 138.0 138.5138.6 Velocity [km/h] Head 144.0 144.8 146.1 144.4 145.3 146.1 144.8146.0 146.6 Velocity [km/h] Spin [rpm] 5456 5412 5301 5390 5500 55265097 5180 5308 Lift Angle 18.8 19.5 20.1 18.7 19.3 19.7 18.7 18.5 19.9[°] Lift Height 38.8 40.5 41.9 35.7 37.1 38.6 37.2 39.2 40.2 [m]

EXAMPLE 2 n-Ni Coated Graphite Composite

Penley Graphite Light LS S-Flex and Penley G2-85×-Flex graphite shaftswere used. The S-Flex shafts were characterized, stripped of the paintand subsequently plated with coarse and fine-grained coatings. PlatedS-Flex shafts and unplated X Flex shafts having a total overall weightof 89 g were performance tested. The Ni sleeves were applied to theoutside of the S-Flex graphite golf club shafts (OD₁=0.5861″, taperingdown to OD₂=0.368″ over a length of 40.5″) by electrodeposition in amodified Watts nickel bath and using a Dynatronix (Dynanet PDPR20-30-100) pulse power supply. The starting mass of each S-Flex shaftwas 71.5 g and prior to electroplating approximately 6.0 g of paint wasstripped off. The coating procedure comprised three steps, namely (1) athin electroless nickel plating to enhance the electrical conductivityusing a procedure and chemicals provided by MacDermid IndustrialProducts (www.macindustrialproducts.com) to achieve an average metalfilm thickness of 0.4 micron at a deposition rate of 1.7 μm/hr and (2)electroplating to form the fine-grained or coarse-grained coating byvarying the duty cycle and the peak current density. The electrolytecomposition was 300 g/l nickel sulfate, 45 g/l nickel chloride, 45 g/lboric acid (H₃BO₃), 2 g/l saccharin and 3 ml/l NPA-91. Standard levelersand brighteners were employed and Inco nickel “R”-rounds were used asanode material. The weight of the metal coating was approximately 20 g.The electroplating conditions and metallic layer properties used aresummarized in Table 2.1.

TABLE 2.1 Electroplating Conditions Fine Coarse Grained GrainedDeposition Temperature [° C.] 60 60 Duty Cycle [%] 25 100 DepositionRate [μm/hr] 50 8.6 Average Coating Thickness: [μm] 55 58 Average GrainSize: [μm] 0.025 10 Ratio Coating Thickness/Grain Size 2,200 5.8 YieldStrength [MPa] 900 276 Hardness [VHN] 580 140

Flexural stiffness was measured with a GolfSmith Frequency Analyzer andthe frequency was converted to a FlexRating (S=stiff, X=extra stiff).The torque values were determined using a GolfSmith Torque Arm with 1ft.lb torque 2″ from the tip end of the shaft. The data are summarizedin Table 2.2 and indicate that a significant improvement in the torquevalues can be obtained by replacing some fraction of the original weightof a graphite shaft with an electrodeposited coating, while maintainingthe overall total weight.

Professional golfers also tested these golf clubs. The feedback receivedsuggested that the clubs made according to this invention exhibited asuperior feel when compared to conventional graphite or steel shafts.Furthermore, the fine-grained coated graphite shafts performed unlikeeither conventional graphite or steel shafts. Compared to graphite, theball trajectory was reported to more consistent, as expected from thesignificantly improved torque value measurements.

TABLE 2.2 Comparison of Golf Shaft Properties Standard Graphite FineCoarse Shaft ID Shaft Grained Grained Graphite Shaft Weight 88.5 71.671.8 Before Coating [g] Deflection Before Coating X S S Torque BeforeCoating [°] 4.4 5.4 5.1 Plating weight [g] N/A 19.2 20.0 Total weight[g] 88.5 88.8 89.8 Deflection After Coating X X X Torque After Coating[°] 4.4 3.6 4.0

One sample was cross sectioned. The microstructure of the plated layerwas confirmed to be quasi-isotropic as illustrated in FIG. 6 b.

Similar performance benefits were achieved when the coated articles werefishing rods, hockey sticks, baseball bats, tennis racquets, bicycleframes and the like as well as automotive, and other industrialcomponents.

EXAMPLE 3 n-Ni Coated Graphite Composite

Example 2 illustrates the benefit of relatively thin, fine-grainedmetallic coatings with a thickness of >25 μm. To investigate the effectof further increasing metal content, hybrid graphite/metal golf shaftswere prepared and characterized. True Temper Prolaunch (A-Flex) drivergraphite shafts were coated with fine-grained and coarse-grainedelectrodeposited metallic nickel layers of varying weights. The processand the characterization techniques employed are described in example 2FIG. 5 shows the torsional stiffness as a function of the metal contentof graphite/metal composite golf shafts. The data reveal that thetorsional stiffness per unit weight of the article containing a metalliccoating representing 50% of the total weight is improved by at leastabout 5% when compared to the torsional stiffness of the same articlenot containing the metallic coating. Further improvements in thetorsional stiffness are obtained when the relative metal content of thehybrid shaft is further increased at a rate of approximately one percentimprovement in torsional stiffness per percent relative metal content.

The torque and deflection data indicate that a significant performanceimprovement can be obtained by increasing the relative metal weight ofthe composite graphite/metal shafts. Graphite/metal composite golfshafts incorporating a metallic coating representing at least 5%,preferably more than 10% and even more preferably more than 20% of thetotal weight provide a substantial improvement over the performance ofuncoated graphite shafts.

Similar performance benefits were achieved when the coated articles werefishing rods, hockey sticks, baseball bats, tennis racquets, bicycleframes and the like as well as automotive, and other industrial parts.

EXAMPLE 4 Faceplate

A 1 mm thick mild steel faceplate as used in golf club driversillustrated in FIG. 1 was plated using a conventional tankelectroplating cell setup and employing the Watts bath as described inExample 2 in order to deposit a 0.4 mm thick layer of fine-grainednickel on one surface. The nickel-layer surface was polished to a“mirror finish” ultimately using 1 μm diamond paste. Subsequently a 0.4mm thick layer of conventional coarse-grained nickel was prepared asdescribed in Example 2. The two samples were suitably mounted on ahorizontal plate and a steel ball (3 mm diameter) was dropped from aheight of 60 cm onto the samples. The rebound height was determined tobe 2.9 mm for the conventional nickel layer, while the rebound height ofthe fine-grained nickel sample was determined to be 28.8 mm. The reboundheight off the fine-grained Ni-sample improved by a factor ofapproximately 10, as expected based on the 10 fold improvement inresilience (Table 4.1).

A conventionally plated sample and one fine-grained sample were crosssectioned. The microstructure of the conventionally plated layer wasconfirmed to be columnar as illustrated in FIG. 6 a, whereas themicrostructure of the fine-grained layer was quasi-isotropic asillustrated in FIG. 6 b.

TABLE 4.1 Electroplating Conditions This Invention Prior Art (finegrained) (coarse grained) Average Coating Thickness: 400 400 [micron]Average Grain Size: [μm] 0.025 20 Grain Size Profile through EquiaxedVariable, Thickness columnar grains Ratio Coating Thickness/ 16,000 20Grain Size Deposition Rate [μm/hr] 45 18 Duty Cycle [%] 25 100Deposition Temperature [° C.] 60 60 Yield Strength [MPa] 900 276Resilience, MPa 1.93 0.18 Rebound height [cm] 28.8 2.9 Improvement inRebound Height [%] 893 0

EXAMPLE 5 Generic Property Comparison

Conventional plate materials were sourced, including an alloy of 17% Cr,4% Ni, balance being Fe and 6% Al, 4% V, balance being Ti. Ni coatingsprepared from a conventional Watts baths were included. Using theplating conditions described in Example 2 and adding and maintainingFeCl₂.H₂O(12 g/l), FeSO₄.7H₂O (81 g/l) and the Na-Citrate (9 g/l) to theWatts bath electrolyte, fine-grained Ni-20% Fe alloy layer coatings wereproduced. A number of mechanical properties are listed in table 5.1 anddepict the advantages of the fine-grained materials according to thisinvention.

A conventionally plated sample and one fine-grained sample were crosssectioned. The microstructure of the conventionally plated layer wasconfirmed to be columnar as illustrated in FIG. 6 a, whereas themicrostructure of the fine-grained layer was quasi-isotropic asillustrated in FIG. 6 b.

TABLE 5.1 Mechanical Properties of Plate Materials Fe—17Cr—4Ni Ti—6Al—4VConventional Ni—20Fe/Fine (Aged) (Annealed) Watts-Ni Grained Grain Size[μm] 50-150 50-150 5-50 0.015 Ultimate Tensile 1,365 895 400 2,250Strength, [MPa] Yield Strength, 1260 830 276 1,785 [MPa] Density,[kg/m³] 7,806 4,429 8,902 8,318 Modulus, [GPa] 197 110 210 185 Strengthto 17 20 4.5 27 Density, [km] Resilience, 4 3 0.18 9 [MPa]

EXAMPLE 6 Faceplate Coating

A nanocrystalline Co—TiO₂ nanocomposite of 0.12 mm average coatingthickness was deposited onto a number of golf head faceplates as inexample 5 using a modified Watts bath for cobalt using a soluble anodemade of electrolytic cobalt pieces and a Dynatronix (Dynanet PDPR20-30-100) pulse power supply. The electrolyte used comprised 300 g/lcobalt sulfate, 45 g/l cobalt chloride, 45 g/l boric acid, 2 g/lsaccharin and 4 ml/I NPA-91. Suspended in the bath were 0-500 g/ltitania particles (<1 μm particle size) with the aid of 0-12 g/l Niklad™particle dispersant (MacDermid Inc.). The electroplating conditions andmetallic layer properties used are summarized in Table 6.1.

In order to achieve a fine-grained coating such as indicated in FIG. 2 aseries of coated samples was produced using the modified Watts bath withthe addition of TiO₂ particles (particle size <1 μm) ranging from 50 g/lto 500 g/l. Table 6.2 illustrates the properties of the deposits.

TABLE 6.1 Electroplating Conditions Deposition Temperature [° C.] 60Duty Cycle [%] 25 Deposition Rate [μm/hr] 40 Average Coating Thickness:[μm] 120 Average Grain Size: [μm] 0.015 Ratio Coating Thickness/GrainSize 8,000

TABLE 6.2 Co—TiO₂ nanocomposite properties TiO₂ Bath Grain FractionConcen- Bath Size of in tration Concentration Co Deposit TiO₂ Dispersantdeposit [Volume Microhardness Sample [g/l] [g/l] [nm] %] [VHN] Control 00 16 0 490 1 50 0 15 19 507 2 100 1.5 15 23 521 3 200 3 17 32 531 4 3006 17 38 534 5 500 12 16 37 541

EXAMPLE 7 Faceplate Coating

A faceplate of a mild-steel golf club head as illustrated in FIG. 1 wascoated using a selective plating unit supplied by Sifco SelectivePlating (www.brushplating.com). A DC power supply was employed. Standardsubstrate cleaning and activation procedures provided by Sifco SelectivePlating were used. Using the anode brush with manual operation a 50 μmthick nanocrystalline Ni˜0.6 wt% P (average grain size: 13 nm, 780 VHN)layer was deposited onto the face plate area of about 3 in². Theelectrolyte used comprised 137 g/l nickel sulfate, 36 g/l nickelcarbonate, 4 g/l phosphorous acid and 2 g/l saccharin. Inco nickel“R”-rounds were used as anode material. The electroplating conditionsand metallic layer properties used are summarized in Table 7.1. Afterplating the faceplate was heat-treated as indicated to further enhancethe mechanical properties by precipitation hardening.

One sample was cross sectioned. The microstructure of the plated layerwas confirmed to be quasi-isotropic as illustrated in FIG. 6 b.

TABLE 7.1 Electroplating Conditions Deposition Temperature [° C.] 65Duty Cycle [%] 100 Deposition Rate [μm/hr] 50 Average Coating Thickness:[μm] 50 Average Grain Size: [μm] 0.013 Ratio Coating Thickness/GrainSize 3,846 Hardness [VHN] 780 Hardness after Heat Treatment 890 (400°C./20 min) [VHN] Hardness after Heat Treatment 1010 (400° C./20 min +200° C./11 hrs) [VHN]

1. A baseball bat having at least one metal, metal alloy or metal matrix composite layer on a metallic or non-metallic substrate, said layer having a thickness between 30 μm and 5 cm, said layer having a microstructure with an average grain size between 0.004 μm and 10 μm and said layer exhibiting a modulus of resilience in the range of 0.25 MPa and 25 MPa and an elastic limit ranging from 0.75% to 2.0%
 2. The baseball bat claim 1 where the substrate is a polymer substrate and said layer has a weight amounting to 5% to 95% of the weight of the baseball bat.
 3. The baseball bat of claim 1 where said layer has a yield strength between 200 MPa and 2750 MPa.
 4. The baseball bat of claim 1 where said layer extends over at least part of the inner surface of said substrate.
 5. The baseball bat of claim 1 where said layer extends over at least part of the outer surface of said substrate.
 6. The baseball bat of claim 1 containing a layer of conductive material between the substrate and the coating.
 7. The baseball bat of claim 1 where the torsional stiffness pursuant weight of the baseball bat is improved at least 5% compared to the torsional stiffness of a baseball bat the same but not containing said at least one metal, metal alloy or matrix composite layer.
 8. The baseball bat of claim 1 wherein said layer contains from 2.5 to 75% by volume of particulate material.
 9. The baseball bat of claim 8 wherein said particulate material is selected from the group consisting of metal powders, metal alloy powders, metal oxide powders, nitride powders, carbide powders, graphite, diamond, nanotubes and polymeric materials.
 10. The baseball bat of claim 1 wherein said layer has a thickness ranging from 35 μm and 5 cm. 